The present invention relates to a liquid detergent formulation for the hand washing of dishes. More particularly, the present invention relates to a detergent formulation for the hand washing of dishes where the persistence of foam in the presence of oily, fatty types of soils is critical to the performance of the detergent.
Liquid hand dishwashing detergent or alternatively referred to as light-duty liquid detergent (LDL) formulations for the cleaning of kitchen surfaces are well known. Kitchen surfaces include counter tops, stove tops, dishes and any other hard surface commonly found in kitchen environments. The term xe2x80x9cdishesxe2x80x9d includes any utensils involved in food preparation or consumption. Kitchen surfaces, particularly dishes, must be washed free of food residues, greases, proteins, starches, gums, dyes, oils and burnt organic residues. As the term xe2x80x9chand dishwashingxe2x80x9d implies, the products typically come into contact with both these hard surfaces to be cleaned and the skin of the person using the product.
Most of the consumer accepted formulations for cleaning dishes with hand dishwashing detergents include anionic surfactants as the primary cleaning ingredients and mildness enhancing, foam stabilizing surfactants such as amine oxides, betaines, and alkanolamides as the secondary surfactants. A significant number of formulations will also include conventional nonionic surfactants (e.g. alcohol ethoxylate, alkyl phenol ethoxylate) and/or specialty nonionic surfactants (i.e. alkyl polyglucoside) to provide the benefits of a mixed active system.
The anionic surfactants in such formulations generally provide the typical high foaming characteristics associated with dishwashing formulations. The foam stabilizing surfactants typically provide the formulation with enhanced product mildness to contacted skin during hand dishwashing and enhanced performance robustness to higher water hardness and to removed soil. This enhanced product performance robustness is typically shown by high levels of foam over a wide range of water hardness levels combined with extended foam persistence during the washing process as more and more soils are deterged into the wash solution.
Foam persistence in the presence of increasing amounts of removed soils throughout the washing session is arguably the most important cleaning efficacy signal relied on by consumers. The hand dishwashing detergent industry uses the laboratory Miniplate Test as the key laboratory appraisal method for assessing this most important performance criterion and to quantify the performance quality of liquid hand dishwashing detergent formulations.
U.S. Pat. No. 5,968,890 B1 discloses a liquid detergent composition for cleansing the skin and hair and comprising a synthetic anionic surfactant, and an amphoteric surfactant and a polyethylene glycol for improved lather.
U.S. Pat. No. 6,268,330 B1 discloses an acidic light duty liquid detergent which is mild to the skin which can be in the form of a clear microemulsion and comprises a sulfate and a sulfonate anionic surfactant and a hydroxy aliphatic acid.
U.S. Pat. No. 6,251,844 B1 discloses an acidic light duty detergent with desirable high foaming and cleaning properties which kills bacteria and is mild to the skin. The light duty liquid detergent comprises an anionic surfactant, zwitterionic surfactant, polyethylene glycol, and a hydroxy acid. The anionic surfactant is present from 10-52 wt-% as a mixture of an alkali metal salt of an anionic sulfonate surfactant and an alkali metal salt of a C8-C18 ethoxylated alkyl ether sulfate or C8-C18 alkyl ether sulfate having a weight ratio of sulfonate surfactant to sulfate surfactant of 20 to 1:1. The zwitterionic surfactant is a water soluble betaine. The light duty liquid detergent further requires a magnesium salt as an essential ingredient to improve overall product performance.
U.S. Pat. No. 6,339,057 B1 discloses a high foaming detergent formulation having a non-ionic base. The reference points out a problem of incompatibility between anionic surfactants and cationic quaternary antimicrobial and the problem that non-ionic surfactants do not normally provide significant foaming capability to liquid formulations.
U.S. Pat. No. 5,955,411 discloses a high foaming light duty liquid detergent having antibacterial properties containing alkyl polyglucoside and polyethylene glycol in order to improve the viscosity of the detergent composition and to improve the flash foam point of the composition.
U.S. Pat. Nos. 5,696,073 B1, 5,700,773 B1, 5,834,417 B1, 5,853,743 B1, 5,854,195 B1, and 5,856,293 B1 disclose a series of light duty liquid cleaning compositions comprising anionic surfactants, specialty co-surfactants, polyethylene glycol, inorganic salts, hydrotroping agents, and an alkyl polyglucoside surfactant, wherein the alkyl polyglucoside is incorporated to provide mildness to human skin.
U.S. Pat. No. 5,998,355 B1 discloses a liquid dishwashing detergent that exhibits increased viscosity, better dissolution rate, and improved cleaning performance in hard water. The liquid dishwashing detergent comprises from about 1 to 90 percent of an anionic surfactant and from about 1 to 30 percent of a solvent hydrotrope selected from the group consisting of alkoxylated glycerides, alkoxylated glycerines, esters of alkoxylated glycerines, alkoxylated fatty acids, esters of glycerine, polyglycerol esters and combinations thereof.
It is an objective of the present invention to provide a light duty liquid detergent which provides improved detergency in hard water and in the presence of oily and fatty types of soils.
It is an objective to produce a light duty liquid detergent which exhibits foam persistence in the presence of oily and fatty types of soils.
It is an objective of the present invention to provide an improved light duty liquid detergent at a lower cost by eliminating exotic materials such as alkyl polyglucoside (APG) surfactants.
The invention relates to a class of compositions for use in light duty liquid, or liquid hand dishwashing detergents which provide excellent performance as measured by persistence of foam in the presence of oily and fatty types of soils. Testing of product performancexe2x80x94based on the stability of foam in the presence of escalating amounts of fatty or oily soils as indicated by the extinction of the foamxe2x80x94showed surprising advantage of the hand dishwashing detergent composition which is essentially free of alkyl polyglucoside, wherein the hand dishwashing detergent comprises at least two different anionic surfactants and a polyethylene glycol.
In one embodiment, the present invention is a liquid dishwashing detergent composition which comprises water, an anionic surfactant mixture containing at least two different anionic surfactants, a polyethylene glycol, and a hydrotrope and/or an inorganic magnesium salt, wherein the liquid dishwashing detergent is essentially free of alkyl polyglucoside (APG) surfactants. The formulation includes a phase stabilizer selected from the group consisting of a hydrotrope, an inorganic salt, and mixtures thereof. The polyethylene glycol employed in the dishwashing detergent formulation of the present invention comprises from about 0.5 to 10 weight percent of the dishwashing detergent and has a molecular weight ranging from about 400 to about 1000.
In another embodiment, the liquid dishwashing detergent consists essentially of: water;
about 5 to 30% by weight of an anionic surfactant;
about 5 to 30% by weight of a co-anionic surfactant;
about 0.5 to 10% by weight of polyethylene glycol;
about 0 to 15% by weight of a foam stabilizing surfactant; and,
about 0 to 15% by weight of optional ingredients;
wherein the polyethylene glycol has a molecular weight ranging from about 400 to about 1000, with the proviso that the liquid dishwashing detergent be essentially free of alkyl polyglucosides. The optional ingredients are selected from the group consisting of hydrotropes, perfumes, colorants, pH adjusting agents, opacifiers, biocidal agents, preservatives, inorganic salts, viscosity modifiers, and mixtures thereof.